Amor fati (lit. "love of fate") is a Latin phrase that may be translated as "love of fate" or "love of one's fate". It is used to describe an attitude in which one sees everything that happens in one's life, including suffering and loss, as good or, at the very least, necessary, in that they are among the facts of one's life and existence, so they are always necessarily there whether one likes them or not. Moreover, amor fati is characterized by an acceptance of the events or situations that occur in one's life. 
This acceptance does not necessarily preclude an attempt at change or improvement, but rather, it can be seen to be along the lines of what Friedrich Nietzsche apparently means by the concept of "eternal recurrence": a sense of contentment with one's life and an acceptance of it, such that one could live exactly the same life, in all its minute details, over and over for all eternity. 
This set design is a half Sun and a half Moon. Sun symbolizes masculinity, bright side of life, and activity. Moon symbolizes femininity, dark side of life, and rest. 
You cannot go through life as an always happy person. There are some bad moments you have to cross. This is only a natural flow of universe where you get to learn "Love of Fate" and ride the tide with all aspects of life.